Doesn't make much sense to keep a modification to prevent escalation with russia a secret - we want ukraine to know so they don't make any plans that rely on capabilities they don't actually have, we want Russia to know so that they don't think they need to pre-empt a strike that isn't coming, and we want everyone else to know that we're not escalating the conflict. The only reason I can think of to keep the modifications a secret would be to bluff that they actually did have the full range, but in that case why not just leave the systems unmodified?